We mentioned on Wednesday that the injury front had been quiet, but as we expected, things picked up (or broke down) between then and now, giving us plenty to cover. Unfortunately for Cubs and White Sox fans, much of that activity came at the expense of Chicago-based players.

Andrew Cashner, CHN (Right rotator cuff strain)

In the last installment of Collateral Damage, we expressed concern about Andrew Cashner's rotator cuff even though he didn't appear to be in severe pain when he was removed from his start. Our suspicision that the rotator cuff might be involved was aroused when he gestured to a particular area of the shoulder when talking to the Athletic Trainer on the mound. Sure enough, while an MRI revealed no major structural damage, it did show a strain to the posterior part of the rotator cuff. While the last thing Cubs fans want to read about is a shoulder injury, this gives us an opportunity to go into detail about a part of the pitcher's anatomy that gets a lot of ink.

The shoulder is a very complex structure in that in order for it to function, it must rely on the muscles surrounding it. (If all the muscles around a hip or elbow waste away, those joints will still function.) The smooth, pain-free motion and stability of the shoulder girdle depends on both dynamic structures (muscles and tendons) and static structures (bones, ligaments, and labrum), including three true articulating joints, one pseudo-joint called the scapulothoracic joint, multiple bones, and approximately 20 different muscles. The muscles you hear about most often are the rotator cuff, biceps, deltoids, pectorals, and the trapezius, or “traps," although others are in some ways equally important (including the latissimus dorsi, serratus anterior, and the rhomboids). When these muscles fail or become fatigued, injuries can occur to other structures.

The rotator cuff is a group of four muscles that have their origins on the shoulder blade and wind their way underneath the acromioclavicular joint (the joint you feel on the very top part of your shoulder) to blend together and attach on the head of the humerus. These muscles fine-tune the movements of the humerus during motion and contribute significantly to the raising and rotation of the arm. As the arm is raised into a throwing position, the rotator cuff draws primarily upon the deltoids to produce a force couple that depresses and rotates the humeral head down, allowing full motion. Without this action during movement, the two bones would bang into each other and allow the arm to be raised only to roughly shoulder level, if that.

Rotator cuff rehabilitation takes longer than, say, a strained quad, because of the relationship between the static stabilizers and the dynamic stabilizers. In injuries to the shoulder related to the rotator cuff, a vicious positive feedback system involving pain, rotator cuff insufficiency, instability, and impingement can develop. The pain alone can last for several weeks (depending on the severity of the injury), increasing demands on the static stabilizers in the shoulder and leading to changes to those structures if the demands are too great (or continue for too long).

Once these static stabilizers are damaged as a result of continued rotator cuff insufficiency, instability develops, which further exacerbates the pain and inflammation arising from impingement of the rotator cuff or biceps tendons. Impingement occurs when the rotator cuff or biceps tendons are pinched between the head of the humerus and the bottom part of the acromioclavicular joint. It is vital to get athletes out of that cycle and introduce exercise and baseball activities gradually, so as to not cause pain and inflammation and restart the process.

Rotator cuff injuries don’t always occur with just a single acute episode. Microscopic changes to the tendons often contribute to the degeneration of the area, and there can be a long period of decline—similar to that observed in an elbow prior to Tommy John surgery—in which a single event only serves as the coup de grâce.

Cashner himself is expected to miss between three to six weeks, depending on how quickly the pain subsides.

Adam Dunn, CHA (Appendectomy)

Dunn underwent an emergency laparoscopic appendectomy on Wednesday, and the pain still hasn’t disappeared as of Thursday. We didn’t expect him to be pain-free the first few days following abdominal surgery, but evidently Dunn has higher expectations, as he is trying to play today. We think he’s likely going to need at least several more days before he can return at full strength, though as is the case with Holliday, once he is back and healed he should hit like nothing ever happened.

Adam Moore, SEA (Knee medial meniscus tear)

During Wednesday’s game, Moore planted his foot and twisted his knee, resulting in a torn medial meniscus. As we discussed in relation to the Astros' Jason Castro a month ago, the medial meniscus is much more likely to be torn than the lateral meniscus, due to its lesser mobility. Hyperflexion of the knee also puts a much greater force on the posterior part of the meniscus (as you can imagine, this would be a problem for catchers).

A date for surgery has not been announced as of yet. In the case of an acute tear, the meniscus is more likely to be repaired rather than just trimmed out. This procedure allows for much better long-term health of the knee, but it also requires a lengthier rehabilitation process. If Moore is placed on the 15-day disabled list, we'll know that the meniscal tear was likely trimmed out. If he's placed on the 60-day disabled list, it's more likely that he had it repaired or that additional procedures were performed. There aren’t too many catchers in the injury database who were reported to have medial meniscal tears, but the range of recovery is 23 days (Jason LaRue in 2006) to 55 days (Joe Mauer in 2004—before he went on the DL a second time that year).

Randy Wells, CHN (Strained right forearm)

Wells began feeling discomfort in his last start of the spring, but it became more of a problem following his start on Monday. As with any forearm strain, there should be some concern that there is something going on in the elbow. Wells has had elbow issues in the past: his 2008 season ended with a stress fracture that caused him to miss the final 13 days of the year. General Manager Jim Hendry did stress emphatically that even though Wells has had elbow injuries in the past, his present injury is nowhere near the elbow and his ulnar nerve is not involved. Wells is going to be shut down for a few weeks before being reevaluated.

Yunel Escobar, TOR (Mild concussion)

Escobar ended up being the first player to go through the official new concussion protocols after hitting his head on Andy LaRoche’s knee while sliding into third base on Wednesday. Any player suspected of a concussion (or a cranial contusion) must follow the National Athletic Trainers Association guidelines for removal from play and be examined in more detail. Athletic trainers or team physicians will then use the SCAT2 tool to further assess the possibility or severity of the concussion, although additional testing is required, including imaging and consultation with a neurologist.

The new 7-day disabled list for concussions is not mandatory, even if the player in question is found to have a concussion—think of it as you would a strained hamstring that is going to keep a player out for just a few games and thus doesn't require a DL stint. What is important is the process—Escobar went through the standardized protocols to diagnose the concussion. When he is ready to play, the Blue Jays have to submit a return-to-play form to Dr. Gary Green, MLB’s medical director, to ensure that the proper procedure has been followed.

Concussions are too individualized to predict exactly when Escobar will return, but if the Blue Jays thought it would take a long time they would already have placed him on the disabled list (though he can always be placed there retroactively if their initial evaluation turns out to have been optimistic). He will likely be ready within a week, but there are no guarantees—Justin Morneau's concussion was considered mild, after all.

Tsuyoshi Nishioka, MIN (Fractured left fibula)

Nick Swisher slid late into second base (and in the process, Nishioka) while attempting to break up a double play in Thursday’s game, which forced Nishioka to the disabled list with a fractured left fibula. The fibula typically takes anywhere from four to eight weeks to heal (the shortest time we have on record is four weeks, but most non-pitchers fall into the six-to-seven-week range). We shouldn’t be surprised that Nishioka is injured, given his history, though it's hard to say this one is his fault.

Flesh Wounds: Michael Wuertz strained his left hamstring last week and was placed on the DL retroactive to April 2nd. … Tigers reliever Ryan Perry landed on the 15-day disabled list with an eye infection. … Takashi Saito strained his left hamstring, but the Brewers don’t expect him to need a DL stint at this point. … Scott Podsednik is still a couple of weeks away from playing in the majors due to his chronic plantar fasciitis. … Joe Thatcher had a setback inhis shoulder rehabilitation, putting an April return in jeopardy. … Brad Lidge agrees with Charlie Manuel about likely not being back before the All-Star break as he recovers from a posterior rotator cuff strain. Score one for CHIPPER

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Nishiola failed to jump out of the way of Swisher. If that is a tendency, then it is his "fault" in the sense of whether it is predictive.
I hear a guy on the radio saying that Nishioka wasn't playing the double play properly at all.
Swisher visited Nishioka after the game to offer his apologies and sympathies. That wasn't just Swisher trying to be extra respectful after having learned about NPB players from Hideki Matsui. That was just genuine Swisher class in action. Not all players would care enough to do that. Swisher has that sort of "band-of-brothers" attitude towards all his fellow MLB-ers that you'd like to see more of from other players. THis is the same guy who embraced Milton Bradley with the A's. The Yankees are lucky to have Nick Swisher.
Thanks, Nick.
I'm a little concerned that maybe the Twins might be at fault in not training Nishioka to make the adjustment to be able to deke the hard slide in MLB. A 2B has to be able to make that last split second leap over the leg of the sliding runner. Mental lapse by Nishioka? Or organizational screwup?
It is worth noting that Nishioka is in his first professional season as a second baseman after transitioning from shortstop, and that particularly on the double play, switching from one middle infield position to the other isn't an automatic by any means.
Outward appearances do consistently suggest that Swisher is a good egg.